Mechanisms of Immune Interaction and T-Cell Reprogramming in the Senescent Lymphoma Microenvironment

Cellular senescence is a protective mechanism that stops damaged or stressed cells from dividing. In cancer, therapy-induced senescence (TIS) can suppress tumor growth, but persistent senescent cells may also contribute to relapse, therapy resistance, and chronic inflammation. In B-cell lymphomas, particularly aggressive types like diffuse large B-cell lymphoma (DLBCL), senescence plays a dual role. While it can initially promote immune-mediated tumor clearance, over time senescent tumor cells may acquire stem-like features and promote immune evasion. We aim to investigate how senescent lymphoma cells interact with the immune system and how this affects tumor progression or control. Our central hypothesis is that senescent lymphoma cells produce specific peptides that activate T cells via MHC-TCR interactions. We will analyze the T cell response to these senescence-associated peptides and characterize the TCR repertoire using single-cell RNA sequencing. Furthermore, we will assess the role of SUV39H1 and BCL2—key regulators of senescence—in maintaining the senescent state and affecting immune surveillance. The Eμ-Myc transgenic mouse model, which closely resembles human aggressive B-cell lymphomas, will be used. We will compare tumor-bearing mice with intact senescence signaling (Eμ-Myc) and senescence-deficient genotypes (SuV39h-/-;Bcl2), both with and without chemotherapy. Six groups will be analyzed at two time points (7 and 14 days post-treatment) to assess short- and long-term effects. Key methods include: Peptide incubation and IFNγ staining to assess T cell activation. Single-cell RNA sequencing for TCR repertoire analysis. High-dimensional tissue imaging (MACSima) to map immune cell populations. Animal experiments are essential to study the complex, systemic immune response in a living organism. There are no in vitro alternatives for these questions. A total of 78 mice will be used, sourced from existing breeding colonies at MDC (C57Bl/6N background). This minimizes the need for additional breeding and aligns with the 3R principles. Only the minimum number of animals needed for statistical relevance and method validation will be used.